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Short-Term Investments | 3 Months Ended
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Mar. 31, 2023
Short-Term Investments |
Short-Term Investments | 4.Short-Term Investments The following table summarizes the short-term investments held at March 31, 2023 and December 31, 2022 (in thousands): ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | ​ | ​ |  | Gross Unrealized |  | Gross Unrealized |  | ​ | ​
​ | ​ | Amortized Cost | ​ | Gains | ​ | Losses | ​ | Fair Value
March 31, 2023 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Corporate debt securities | ​ | $ | 6,082 | ​ | $ | — | ​ | $ | (7) | ​ | $ | 6,075
Treasury bills | ​ | ​ | 4,949 | ​ | ​ | 3 | ​ | ​ | — | ​ | ​ | 4,952
Total | ​ | $ | 11,031 | ​ | $ | 3 | ​ | $ | (7) | ​ | $ | 11,027
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | Gross Unrealized | ​ | Gross Unrealized | ​ | ​ | ​
​ |  | Amortized Cost |  | Gains |  | Losses |  | Fair Value
December 31, 2022 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Corporate debt securities | ​ | $ | 16,508 | ​ | $ | — | ​ | $ | (63) | ​ | $ | 16,445
Treasury bills | ​ | ​ | 5,983 | ​ | ​ | — | ​ | ​ | (3) | ​ | ​ | 5,980
Yankee securities | ​ | ​ | 2,000 | ​ | ​ | — | ​ | ​ | (1) | ​ | ​ | 1,999
U.S. agency bonds | ​ | ​ | 3,000 | ​ | ​ | — | ​ | ​ | (12) | ​ | ​ | 2,988
Reverse repurchase agreements | ​ | ​ | 178,500 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | 178,500
Total | ​ | $ | 205,991 | ​ | $ | — | ​ | $ | (79) | ​ | $ | 205,912
​ The contractual maturities of all short-term investments held at March 31, 2023 and December 31, 2022 were one year or less. There were 3 and 16 short-term investments in an unrealized loss position with aggregate values of $6.2 million and $25.6 million as of March 31, 2023 and December 31, 2022, respectively. These investments were in a loss position for less than 12 months and the Company considered the loss to be temporary in nature. The Company considered the decline in market value for these securities to be primarily attributable to economic and market conditions. As of March 31, 2023, the Company did not intend to sell, and it was not likely that the Company would be required to sell, the investments that were in an unrealized loss position before recovery of their amortized cost basis. Accordingly, the Company did not recognize any other-than-temporary impairments related to its short-term investments in an unrealized loss position. ​ Gross realized gains and losses on the sales of short-term investments are included in other income, net. Unrealized holding gains or losses for the period that have been included in accumulated other comprehensive income, as well as gains and losses reclassified out of accumulated other comprehensive income into other income, net, were not material to the Company’s condensed consolidated results of operations. The cost of investments sold or the amount reclassified out of the accumulated other comprehensive income into other income, net is based on the specific identification method for purposes of recording realized gains and losses. All proceeds in the three-month periods ended March 31, 2023 and 2022 related to maturities of underlying investments. The gains on proceeds from maturities of short-term investments were not material to the Company’s condensed consolidated results of operations for the three months ended March 31, 2023 and 2022.

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